The invention relates to improvements in controlled deflection rolls such as used in papermaking machines.
More particularly, the invention relates to a self-loading type of controlled deflection roll wherein a roll shell is journalled on a shaft having means for supporting the shell along the nip line, and a unique and particular structure is provided for preventing axial displacement of the shell relative to the shaft.
Controlled deflection rolls of various designs have been utilized in the art, including those disclosed in U.S. Pat. Nos. 4,821,384 of Arav et al and 5,060,357 to Roerig et al. In these patents, the roll shell is hydrostatically supported in the direction of its nip formed with another roll such as by a plurality of shoes which are aligned longitudinally along the length of the stationary support shaft. Various structural arrangements are utilized to permit deflection of the roll shaft as it supports the roll shell. In addition to stabilization in the rotary direction, stabilization of the rotating roll shell relative to the shaft must be obtained in an axial direction. Arrangements heretofore used, such as those disclosed in U.S. Pat. No. 5,060,357, involve providing relatively extensive equipment which is carried within the roll shell and cannot easily be serviced. These arrangements use hydraulic pistons between the stationary center shaft and stabilizing side shoes to provide for axial misalignments and differential linear expansion between the roll shell and the center shaft. Such pistons and hydrostatic bearing pads must be activated at all times during operation of the roll. This, in addition to requiring complicated expensive equipment, adds to the total power requirements in order to provide for the necessary fluid flow. Also, there is the disadvantage of the shell not being held axially when the hydraulic system is not operating.
Accordingly, it is an object of the present invention to provide an improved axial alignment-maintaining means between a rotating roll shell and its supporting shaft which avoids disadvantages heretofore in mechanisms available.
A further object of the invention is to provide an axial alignment-maintaining means between a controlled deflection roll shell and its supporting shaft eliminating requirements for hydraulic pressures to be piped within the roll shell and providing mechanisms which have reliable, long operating life.